Process for the preparation of a polyurethane from a storage stable polyol compositions

ABSTRACT

Disclosed is a storage stable blend of a long chain polyol and a short chain diol wherein the diol is present in an amount whereby the diol and polyol form an incompatible blend. The blend is rendered storage stable by the addition of a compatibilizing amount of a urethane.

This is a division of co-pending U.S. patent application Ser. No.185,252, filed 04/20/88, now U.S. Pat. No. 4,839,087, which in turn is acontinuation of U.S. patent application Ser. No. 071,236, filed07/09/87, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to polyol blends such as are used inpreparation of molded parts and more particularly to the stabilizationof such polyol blends and to improved thermoset molded parts madetherefrom.

Reaction Injection Moldings (RIM) are urethanes basically consisting ofa polyol and a polyisocyanate, usually with an extender (e.g. a glycolor a diamine), optionally with a blowing agent (e.g. air), optionalreinforcing material (e.g. glass, mica, etc.), wetting agents, and thelike, which materials are high pressure injected through a mixing headinto a pre-heated mold with usual post-molding baking thereafterapplied. RIM urethanes can range from low modulus to very high modulusmaterial parts, foamed on the interior but with a smooth surface. RIMurethanes are capable of being made into very large one-piece partswhich are very light in weight. Typical present-day uses of RIM partsinclude, for example, automobile parts (e.g. bumpers, air deflectors,fenders, front ends, etc.), business machine housings, ski boots, officefurniture, and a wide variety of products.

When a glycol extender is utilized in conjunction with a long chainpolyol, such as a long chain polyoxyalkylene polyol, it has beenreported that the blend suffers from storage stability by separatinginto two phases. Such phase separation creates difficulties at the plantsince mixing of the phase-separated blend must precede use of the blendwhether such blend is utilized in RIM part formation or is utilized forother purposes. A variety of proposals aimed at rendering the mixture oflong chain polyol and short chain diol compatible have appeared in theart. For example, U.S. Pat. No. 3,929,730 proposes to compatibilize theblend of a polyol and 1,4-butanediol by the addition of thiodiglycol orphenylenediethanolamine. U.S. Pat. No. 3,993,576 proposes tocompatibilize mixtures of high molecular weight polyols and lowmolecular weight polyols by the addition of a butylene glycol orpropylene glycol such as dibutylene glycol. U.S. Pat. No. 4,220,732proposes to compatibilize the blend of polyol and glycol by utilizing asthe glycol extender a combination of 1,4-butanediol andphenyldiethanolamine. U.S. Pat. No. 4,385,133 compatibilizes thepolyol/glycol blend by employing as the polyol component a mixture ofspecific polyoxypropylene polyoxyethylene polyols of specific molecularweight and functionality. U.S. Pat. No. 4,485,032 discloses ureas orsubstituted ureas as compatibilizing agents for long chain polyols andup to 30% ethylene glycol. Amounts in excess of 30% resulted in gelled,unuseable products. Other proposals involve the use of salts (potassiumchloride or potassium acetate) or add a small amount of isocyanate forpartial reaction and compatibilization of the blend. These prior artcompatibilizing agents suffer from several deficiencies, primarily lowextender levels allowed, high viscosity of resulting mixtures andlimited applicability.

Despite such advances in the art, need for effectively stabilizing thepolyol/glycol blend while improving the final product still is a desireof the art.

BROAD STATEMENT OF THE INVENTION

The present invention is addressed to compatibilizing an incompatibleblend of a long chain polyol, such as a long chain polyoxyalkylenepolyol, and short chain diol, such as a glycol. Such method comprisesincorporating into the blend a compatibilizing amount of a urethane.

Another aspect of the present invention is the resulting compatibilizedblend of long chain polyol, short chain diol, and compatibilizingurethane. Other aspects of the present invention will readily appear tothose skilled in the art based upon the disclosure contained herein.

Advantages of the present invention include the ability to effectivelyand efficiently compatibilize a blend of polyol and glycol for making apractical storage stable product. Yet another advantage is the increasedcompatibility of urethane modified polyol blend and isocyanate which isachieved. A further advantage is the ability to make tough and rigidthermosets via the simultaneous polymerization of hydroxy/isocyanatefunctionality and ethylenic unsaturation functionality. These and otheradvantages of the present invention will be readily apparent from thedescription which follows.

DETAILED DESCRIPTION OF THE INVENTION

The three prime ingredients of the compatibilized blend are a long chainpolyol, a short chain diol, and a compatibilizing urethane. Referringinitially to the urethane, it has been found that urethanes useful inthe practice of the present invention include those of: Formula I:##STR1## where R and R' independently represent an alkyl group havingfrom 1 to 20 carbon atoms, an aryl group having from 6 to 12 carbonatoms, an alkaryl group having from 7 to 20 carbon atoms, hydroxyl,hydroxyalkyl or hydroxyaryl; and Formula II: ##STR2## where R and R'independently represent an alkyl group having from 1 to 20 carbon atoms,an aryl group having from 6 to 12 carbon atoms, an alkaryl group havingfrom 7 to 20 carbon atoms, hydroxyl, hydroxyalkyl or hydroxyaryl.

The proportion of compatibilizing urethane is an amount effective formaking the blend of long chain polyol and short chain diol storagestable or phase-stable. Such effective amount typically translates intoa percentage of urethane ranging from about 1 to about 20 andadvantageously between about 2 and about 10. Of course, mixtures of theurethanes may be utilized as is necessary, desirable, or convenient.

The foregoing description illustrates the presently preferred embodimentof the present invention wherein a long chain polyol and short chainglycol incompatible mixture is compatibilized by a urethane. It shouldbe realized that addition of additional long chain polyols to suchthree-component mixture usually will affect the amount of urethanerequired for compatibilizing the incompatible blend. Thus, the weightratio noted above is illustrative only and may be required to beadjusted to a significant degree on occasion.

Referring to the incompatible blend of long chain polyol and short chaindiol, RIM technology requires levels of short chain diol to be such thatthe solubility level of the short chain diol in the long chain polyol isexceeded; thus the lack of storage or phase stability. The short chaindiols most often are alkylene glycols typically ranging from about 2 to8 carbon atoms in length. Alternatively, the short chain diols can bepolyoxyalkylene glycols resulting from the reaction of an alkylene oxide(e.g. ethylene oxide, propylene oxide, or the like) with a short chainalkylene glycol. Advantageously the short chain diols used are propyleneglycol/dipropylene glycol mixtures, with minor (less than 50% of thetotal short chain diol) amounts of other diols such as ethylene glycol,diethylene glycol, 1,4-butanediol, 1,6-hexanediol, and the like. Theratio of propylene glycol to dipropylene glycol can be from about 5:1 toabout 1:20. It has been found that extremely high levels of short chainglycols, not possible with prior art compatibilizing agents, can formcompatible mixtures with the present invention. The ratio of short chaindiol to long chain polyol can be from about 1:4 to about 3:1.

Referring to the long chain polyols, such polyols typically arepolyoxyalkylene polyols with average molecular weight ranging frombetween about 500 and about 20,000 and include diols, triols, tetraols,graft or polymer polyols, and the like. The majority of oxyalkylenegroups are oxyethylene or oxypropylene groups including mixturesthereof. Additional examples of long chain polyols can be found in U.S.Pat. Nos. 4,385,133, 3,929,730, 3,993,576, and 4,227,032.

The urethane-compatibilized blend is storage or phase stable which meansthat the compatibilized blend exhibits single phase characteristics whenstored at, for example, room temperature, for a time period of at leastthree months though typically storage of up to six months may berequired. Additionally, the compatibilized blend exhibits thermalstability by exhibiting no significant increase in viscosity whensubjected to storage at elevated temperature of, for example, about 100°C. Additionally the compatibilized blend can be subjected to multiplefreeze-thaw cycles and still exhibit single phase characteristicswherein no significant increase of viscosity can be detected. Theability to exhibit single phase characteristics with no significantincrease in viscosity renders the compatibilized blend "storage stable"for present purposes.

Any of the organic polyisocyanates commonly employed in the art ofpreparing polyurethanes can be employed in forming urethane parts fromthe compatibilized blend of the present invention. Such polyisocyanatesoften are polymeric isocyanates in order to reduce toxic vapors ofisocyanate monomers. Further, alcohol-modified and other modifiedisocyanate compositions (e.g. thiocyanates) may be used. Polyisocyanatespreferably will have from about 2-4 isocyanate groups per molecule informing urethane parts. Suitable polyisocyanates for use in the presentinvention include, for example, hexamethylene diisocyanate, 4,4'-toluenediisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethylpolyphenyl isocyanate (polymeric MDI or PAPI), m- and p-phenylenediisocyanates, bitolylene diisocyanate, triphenylmethane triisocyanate,tris-(4-isocyanatophenyl) thiophosphate, cyclohexane diisocyanate(CHDI), bis-(isocyanatomethyl) cyclohexane (H₆ X DI),dicyclohexylmethane diisocyanate (H₁₂ MDI), trimethylhexanediisocyanate, dimer acid diisocyanate (DDI), dicylcohexylmethanediisocyanate, and dimethyl derivatives thereof, trimethyl hexamethylenediisocyanate, lysine diisocyanate and its methyl ester, isophoronediisocyanate, methyl cyclohexane diisocyanate, 1,5-naphthalenediisocyanate, triphenyl methane triisocyanate, xylylene diisocyanate andmethyl and hydrogenated derivatives thereof, polymethylene polyphenylisocyanates, chlorophenylene-2,4-diisocyanate, and the like and mixturesthereof. Aromatic and aliphatic polyisocyanate dimers, trimers,oligomers, polymers (including biuret and isocyanurate derivatives), andisocyanate functional prepolymers often are available as preformedpackages and such packages are suitable for use in the present inventionalso.

The proportion of isocyanate groups to hydroxyl groups in theurethane-forming composition (isocyanate index) typically will rangefrom about 0.8:1 to about 1.2:1, though such ratio can vary as is wellknown in this art. The two packages or streams which are utilized informing RIM parts comprise the compatibilized blend as one stream andthe polyisocyanate as the second stream. Each stream may containappropriate catalytic amounts of catalysts which promote the reactionbetween hydroxyl groups and isocyanate groups. Urethane-promotingcatalysts are well known in the art and include a wide variety oforganic and inorganic salts of, and organometallic derivatives of,bismuth, lead, tin, and the like, as well as organic phosphines andtertiary organic amines. The art cited above contains exemplary lists ofsuch catalysts and should be referred to for a further descriptionthereof.

Other commonly used additives for RIM products can be applied to thepresent invention provided that they are inert to the stability andreactivity of the composition. Such additives include, for example,fillers, blowing agents, reinforcing agents, dyes, pigments, moisturescavengers, diluents, surfactants, mold release agents, and the like.

The following examples show how the present invention has beenpracticed, but should not be construed as limiting. In this application,all units are in the metric system, and all percentages and proportionsare by weight, unless otherwise expressly indicated. Also, all citationsset forth herein are expressly incorporated here by reference.

EXAMPLES 1-17

Incompatible mixtures of long chain polyols and short chain diols wereprepared using the compatibilizers of the present invention comparedwith known compatibilizers and with the absence of compatibilizers. Theformulations and test results are set forth below. The indicated amountsof the various components were mixed and heated if necessary, allowed tocool to room temperature and observed. Miscibility was indicated when aclear, homogeneous solution was attained with no phase separation aftersetting for seven days.

                  TABLE 1 (A)                                                     ______________________________________                                                  EXAMPLE NO.                                                         Composition*                                                                              1        2      3      4    5                                     ______________________________________                                        Incompatible                                                                  Mixture                                                                       Propylene Glycol                                                                          15       15     20     15   15                                    Dipropylene Glycol                                                                        10       10     10     10   10                                    Polyol A    15       15            15   15                                    Polyol C                    20                                                Compatibilizer                                                                M           2        4                                                        N                           10                                                U                                       15                                    Miscibility No       No     No     No   Yes                                   ______________________________________                                         *Polyol C  TP4040 (BASF), a 4,000 molecular weight triol based on poly        (propylene glycol).                                                           Polyol B  SF 5505 (Texaco), a 5,000 molecular weight based on poly            (propylene glycol).                                                           Polyol A  Voranol 2148 (Dow Chemical), a 7,200 molecular weight polyether     triol based on poly (propylene glycol).                                       Polyol D  Niax 3128 (Union Carbide), a 6,000 molecular weight triol           modified with grafted polyol acrylonitrile.                                   Compatibilizer:                                                               M  Urea                                                                       N  Tripropylene glycol                                                        U  Ethyl carbamate                                                            V  Oxazolidone                                                                W  4,4dimethyl oxazolidone                                                    X  N(n-butyl)-2-hydroxypropyl carbamate                                       Y  4ethyl-(N-hydroxyethyl)-4-hydroxymethyl oxazolidone                        Z  N(n-propyl) ethyl carbamate                                           

                  TABLE 1 (B)                                                     ______________________________________                                                  EXAMPLE NO.                                                         Composition 6      7       8     9    10   11                                 ______________________________________                                        Incompatible                                                                  Mixture                                                                       Propylene Glycol                                                                          15     15      30    30   15   15                                 Dipropylene Glycol                                                                        10     10      10    10   10   10                                 Polyol C    15                                                                Polyol A           15                                                         Polyol B                   27    27                                           Polyol D                              15   15                                 Compatibilizer                                                                U           3              4               2                                  V                  2                                                          Miscibility Yes    Yes     Yes   No   No   Yes                                ______________________________________                                    

                  TABLE 1 (C)                                                     ______________________________________                                                      EXAMPLE NO.                                                     Composition     12     13       14   15                                       ______________________________________                                        Incompatible                                                                  Mixture                                                                       Ethylene Glycol                      2                                        Propylene Glycol                                                                              15     15       20   13                                       Dipropylene Glycol                                                                            10     10       10   10                                       Polyol A        15                                                            Polyol C               15       20                                            Polyol B                             18                                       Compatibilizer                                                                W               2                                                             X                      2             3                                        Y                               3                                             Miscibility     Yes    Yes      Yes  Yes                                      ______________________________________                                    

                  TABLE 1 (D)                                                     ______________________________________                                                         EXAMPLE NO.                                                  Composition        16     17                                                  ______________________________________                                        Incompatible                                                                  Mixture                                                                       1,4-Butanediol     5                                                          Propylene Glycol   10     15                                                  Dipropylene Glycol 10     10                                                  Polyol B           10                                                         Polyol C                  15                                                  Compatibilizer                                                                W                  2                                                          Z                         2.7                                                 Miscibility        Yes    Yes                                                 ______________________________________                                    

EXAMPLE 18

The polyol/diol compatibilized mixture of Example 5 (41.5 g, 0-55hydroxyl equivalent) was mixed by hand with 0.05 g dibutyltin dilaurateand 83.2 g (105 isocyanate index) of a modified liquid MDI product(equivalent weight=144 g). This mixture was then poured into a moldheated to 90° C. After three minutes a hard, tough opaque panel hadformed and was removed from the mold.

I claim:
 1. In a process for the preparation of a polyurethane byreaction of an organic polyisocyanate and a blend comprising a longchain polyol and a short chain diol, said blend phase separating understorage, the improvement which comprises incorporating into said blend acompatibilizing amount of a urethane corresponding to Formula I or II##STR3## wherein R and R' independently represent an alkyl group havingfrom 1 to 20 carbon atoms, an aryl group having from 6 to 12 carbonatoms, an alkyaryl group having from 7 to 20 carbon atoms, hydroxyl,hydroxyalkyl or hydroxyaryl and using said compatibilized blend forforming said polyurethane.
 2. The process of claim 1 wherein theurethane is present in a weight perent of from about 1 to about
 20. 3.The process of claim 1 wherein the proportion of short chain diol insaid blend ranges from about 1 to 4 to about 3 to
 1. 4. The process ofclaim 1 wherein said polyol comprises a polyoxyalkylene polyol having amolecular weight of between about 500 and about 20,000.
 5. The processof claim 1 wherein said diol comprises a C₁ -C₈ alkylene glycol.